LOWELL — Alex Santostefano is just making up for lost time.

An ACL tear in practice forced the junior to sit out last season and watch from the sideline as Austin Prep captured the Division 3 North softball title. On Saturday morning, the East Boston resident led the top-seeded Cougars to their fourth straight sectional championship, recording both RBIs — including the eighth-inning walkoff single — in a tight 2-1 win over Catholic Central rival third-seeded St. Mary’s at Martin Field in Lowell.

“It feels amazing, coming back,” Santostefano said. “I was bummed last year that I couldn’t play, but I knew that I’d come back the next year and bring it home with them.”


Austin Prep (22-2) will play South champion Case in a state semifinal this week (TBA).

In the bottom of the eighth, Santostefano launched a deep ball to right field to score Lauren Sablone, who had reached on a single and took second on a passed ball. The pair also teamed up in the first inning when the Cougars went ahead, 1-0, on Santostefano’s single.

“We know Lauren gets on base, we’ve got the speed factor,” said Austin Prep coach Frank Sorrenti. “We just wanted to move her around.

“[Santostefano] stayed hot today and got a big hit when it really mattered.”

Sablone (3 for 4, two runs) was also strong defensively, grabbing five fly balls that went her way in center.

Freshman Lily Newhall put up a fight for St. Mary’s (19-5), fanning seven and scattering six hits. For Austin Prep, Serena Gilbride allowed seven hits, striking out one.

“Our players, they want to play softball, and they want to be good at it,” Sorrenti said. “They’re always optimistic. They never give up and just keep grinding away, and that’s why we’re able to do this kind of thing.”


Jenna Ciccotelli can be reached at jenna.ciccotelli@globe.com.